1. Field of the Invention
The present invention relates to a linear light source module and an optical assembly for a scanner using such linear light source module, and more particularly to a linear light source module with two light guides and an optical assembly for a scanner using such linear light source module.
2. Related Art
Light-emitting diodes (LEDs) have been widely used as light sources because the LED advantageous has the high energy conversion efficiency, the power-saving property, the long lifetime, the small size and the like. In a scanner, the LED acts as a point light source for outputting light, which needs to be converted into a linear light source by a light guide so that the illumination light required to scan an original can be provided.
The typical light guide functions for the purpose of guiding light. So, almost the light guides are made of a transparent acrylic material by way of injection molding, where the injection molded product has one gate or multiple gates to facilitate the injection molding. In a longitudinal light guide, the gate is usually disposed on one end of the injection molded product so that the designer can effectively control the deformation, disorder, residual stresses and the like. The presence of the gate would not affect the illumination quality of the light guide when such the light guide is used in an illumination light source where the light is inputted from one single side of the light guide.
In order to make the linear light source module have higher illumination at two ends, dual-LED linear light source modules have been recently used, wherein LEDs are disposed on two ends of the light guide. However, the light guide has to be additionally trimmed by way of machining one end formed with a gate, or otherwise the light beam of the LED cannot effectively enter the light guide and the illumination of the light guide is indirectly affected.